The present invention relates to a hydrocarbon conversion process and a catalyst composition to be utilized in said hydrocarbon conversion process. More particularly, the invention relates to an improved alkylation process for the production of an alkylate product by contacting hydrocarbon with a novel catalyst composition.
The use of catalytic alkylation processes to produce branched hydrocarbons having properties that are suitable for use as gasoline blending components is well known in the art. Generally, the alkylation of olefins by saturated hydrocarbons, such as isoparaffins, is accomplished by contacting the reactants with an acid catalyst to form a reaction mixture, settling said mixture to separate the catalyst from the hydrocarbons, and further separating the hydrocarbons, for example, by fractionation, to recover the alkylation reaction product. Normally, the alkylation reaction product is referred to as “alkylate”, and it preferably contains hydrocarbons having seven to nine carbon atoms. In order to have the highest quality gasoline blending stock, it is preferred that the hydrocarbons formed in the alkylation process be highly branched.
One of the more desirable alkylation catalysts is hydrofluoric acid, however, the use of hydrofluoric acid as an alkylation catalyst has certain drawbacks. One of the primary problems with the use of hydrofluoric acid as an alkylation catalyst is that it is a highly corrosive substance and it is toxic to human beings. The toxicity of hydrofluoric acid to human beings is further complicated by the fact that anhydrous hydrofluoric acid is typically a gas at normal atmospheric conditions of one atmosphere of pressure and 70° F. It is possible for the vapor pressure of hydrofluoric acid at standard atmospheric conditions to create certain safety concerns when it is exposed to the atmosphere. These safety concerns are created by the ease with which hydrofluoric acid is vaporized and released into the atmosphere.
In spite of the potential problems with human toxicity and the corrosive characteristics of hydrofluoric acid, industry has in the past determined that the benefits from the use of hydrofluoric acid as an alkylation catalyst outweigh the potential problems. For instance, hydrofluoric acid is an extremely effective alkylation catalyst in that it permits the reaction of olefins by isoparaffins at low process pressures and process temperatures. HF is particularly suited for use as a catalyst in the alkylation of butylenes and, in the case of the alkylation of propylene and amylenes, HF has been used as an effective catalyst whereas other alkylation catalysts, such as sulfuric acid, have been found to be not as effective in such alkylation services. Additionally, the alkylate formed from a hydrofluoric acid alkylation process is of a very high quality having such desirable properties as being a mixture of highly branched hydrocarbon compounds that provide a high octane motor fuel. Generally, it has been found that the alkylate produced by a hydrofluoric acid alkylation process has a higher octane value than that produced by typical sulfuric acid alkylation processes. Thus, it would be desirable to use an alkylation catalyst that has the desirable features of hydrofluoric acid catalyst but without having its high vapor pressure.